Rejuvenated Ireland secured the bonus-point victory that ensured qualification for the quarter-finals, despite playing the final 52 minutes with only 14 men after centre Bundee Aki became their first player to be sent off in a Rugby World Cup match.
While Ireland could yet face South Africa in the last eight, their more likely opponents are defending champions New Zealand.
"You've got to be at your very, very best to have a chance. They're not back-to-back World Cup winners for no reason," Ireland coach Joe Schmidt said. "For us it would be, to a degree, a mountain to climb. But if it is the All Blacks we'll look to scale those heights."
Regardless of the opposition, Schmidt is likely to be without Aki, but on the bright side he will otherwise have a fully fit squad to choose from. Four years ago, Ireland won a bruising encounter with France in Cardiff in their final pool game. Decimated by injury they lost badly to Argentina. Now they move on with their momentum restored.
After confidence-sapping performances against Japan and Russia, Ireland needed to put down a marker ahead of the knockouts and it took them only three minutes to show their intent.
Captain Rory Best found Iain Henderson with a lineout throw close to the Samoa line and then got himself on the end of a rolling maul the underdogs could not cope with. Johnny Sexton kicked the extras from the touchline and his team had the emphatic start they needed.
The Samoan cause was not helped when hooker Seilala Lam was shown a yellow card after a shoulder hit to the head of Jacob Stockdale, with referee Nic Berry deciding not to issue a red because the Irish winger was bent low when the contact was made.
It took Ireland just three minutes to exploit their numerical advantage. Rampaging prop forward Tadhg Furlong beat four defenders to score a third try from his past four starts.
Sexton, who was controlling the game beautifully, converted from the 22m line and then turned try-scorer on 20 minutes when set free by an electric line break by Jordan Larmour, the Player of the Match.
Twenty-five minutes in, Samoa finally fired a shot, with captain Jack Lam forcing his way over following a lineout. It was a reminder of the Samoans' physicality and power and gave them a glimmer of hope.
Three minutes later, Berry pulled the red card from his pocket, pictured, and there were gasps around a stadium full of Irish fans.
The first hint of trouble came when Robbie Henshaw fired a ball over Stockdale's head. In the ensuing scramble Aki - who is of Samoan descent - hit the ball-carrier UJ Seuteni high and hard with a shoulder that sent him crashing to the turf, clearly concussed.
While the tackle was poorly executed rather than malicious, this time the official could find no mitigating circumstances. It was only the third time an Irish player had been shown a red card in the professional era and the first since June 2016, when CJ Stander was sent off against his native South Africa.
After the game, Samoa coach Steve Jackson expressed sympathy for Aki and hope that he will escape suspension, but Schmidt seemed resigned to losing his man for at least one game.
"It's a really tough situation," Schmidt said. "It's all split-second stuff. We live in hope and we'll see what the judiciary decide. Once it's a red card, you sense a loss of control over what happens next.
"I certainly feel for Bundee. He's obviously devastated that any further participation in the tournament is now at risk. There is a very hard line being taken and we'll just have to accept whatever decision is made."
Any fears that Ireland might unravel after Aki's departure were put to bed two minutes before the interval when Sexton again exposed hesitancy in the Samoa defence to run in the bonus-point try, pictured above, and give his team a 26-5 lead at the interval.
After that, it was just a case of how many more tries Ireland would add and Conor Murray's brilliant cut-out pass on 48 minutes sent Larmour in for the fifth. Sexton converted and was promptly withdrawn, with his half-back partner Murray quickly following as Ireland's thoughts began moving to Tokyo next weekend.
Replacement lock Jean Kleyn almost provided the sixth try but the TMO could see no grounding. No matter. Stander soon bulldozed his way over after intense Irish pressure.
Andrew Conway came off the bench to pounce on replacement fly-half Joey Carbery's grubber kick and scored the seventh try and his third of the tournament. It was all too easy, but Ireland will not complain. They are back to something close to their best form and now have a shot at making the semi-finals for the first time.